Note: Descriptions are shown in the official language in which they were submitted.
CA 02315578 2000-08-11
CUTTER LINK HAVING A DEPTH LIMITER DIVIDED
INTO A SUPPORT SURFACE AND A TOP SURFACE
Background of The Invention
The present invention relates to a cutter link for the saw chain of a power
chain saw,
and includes a main body that has rivet openings for connection with other
chain links of the
saw chain. When viewed in the direction of travel, the main body has a front
portion and a rear
portion, wherein the rear portion is provided with a cutter tooth having a top
cutter and a lateral
cutting edge, and wherein the front portion is provided with a depth limiter
having a top surface
that faces away from the main body, with the depth limiter also having a
support surface that
is lower than the top cutter.
A cutter link of this general type is known from EP 0 712 700 A1, according to
which the
depth limiter is formed by a tab or tang of a front portion of the main body,
with the tang being
angled off transverse to the direction of travel of the cutter link. For this
purpose, the carrying
element of the depth limiter is first bent away toward that longitudinal side
of the main body
that is provided with the side cutter, with the free end section being bent
back in the opposite
direction by about 90°, so that it points toward the other longitudinal
side of the main body.
To bend away that tang that forms the top surface of the depth limiter, the
free end
section of the carrying element must in the finished state have a length that
corresponds to at
least 1.5 times the thickness of the main body. As a consequence, the depth
limiter
necessarily has a minimum size that is dictated by the manufacturing process.
The top surface of the depth limiter drops off in the direction of travel, so
that the higher
edge fulfills a support function during a cutting process, and at the same
time determines the
chip or cutting thickness of the chip that is to be cut. In this connection,
on the one hand a
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reliable support is to be ensured, for which reason one has tried to keep the
support surface
large. On the other hand, due to the support on the material being cut, a
large support surface
increases the feed pressure that is necessary during the cutting process and
causes the feed
efficiency of the cutter link to drop so that the cutting efficiency also
drops. Although a smaller
support surface leads to a higher cutting efficiency with lower feed pressure,
when a smaller
support surface rests, for example, in soft wood then with increased feed
pressure it
penetrates very deeply into the material and can therefore no longer reliably
ensure the
function of limiting the chip thickness.
In order to achieve an acceptable compromise between the desired high cutting
efficiency on the one hand and the reliable limitation of the chip thickness
due to the depth
limiter on the other hand, in the cutter link pursuant to EP 0 712 700 A1 the
bent away tang
of the depth limiter has a shape that is structurally complicated and
expensive. For example,
the trailing edge of the top surface that faces the cutter tooth is angled off
in the direction of
travel accompanied by the formation of a point that is directed toward the top
cutter; also the
free longitudinal edge of the depth limiter extends at an angle to the plane
of the main body
in such a way that the top surface tapers in the direction of travel.
It is therefore an object of the present invention to improve a cutter link
having a depth
limiter of the aforementioned general type in such a way that with a low
structural and
manufacturing expense a minimally required support surface is made available
forthe effective
limitation of the chip thickness, yet nonetheless excessive penetration of the
support surface
into soft material is reliably prevented.
Brief Description of the Drawings
This object, and other objects and advantages of the present invention, will
appear more
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clearly from the following specification in conjunction with the accompanying
schematic
drawings, in which:
Fig. 1 is a side view of one exemplary embodiment of an inventive cutter link
having a depth limiter;
Fig. 2 is a top view of the cutter link of Fig. 1;
Fig. 3 is a top view of a further exemplary embodiment of an inventive cutter
link;
Fig. 4 is a side view similar to that of Fig. 1 of another exemplary
embodiment
of an inventive cutter link;
Fig. 5 is a side view of a cutter link having a depth limiter that is offset
out of the
plane of the main body;
Fig. 6 is a top view of the cutter link of Fig. 5;
Fig. 7 is a side view of an exemplary embodiment of a further inventive cutter
link having a top surface disposed between the support surface and the
cutter tooth;
Fig. 8 is a top view of the cutter link of Fig. 7;
Fig. 9 is a further exemplary embodiment of a cutter link similar to Fig. 7;
Fig. 10 is a side view of a further exemplary embodiment of an inventive
cutter
link with a top surface disposed between the support surface and the
cutter tooth;
Fig. 11 is a top view of the cutter link of Fig. 10;
Fig. 12 is a side view of a cutter link having an edge of the top surface
disposed
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at the level of the support surface;
Fig. 13 is a side view of a cutter link having both a leading and trailing top
surface
in the direction of travel;
Fig. 14 is a top view of the cutter link of Fig. 13;
Fig. 15 is cross-sectional view through a saw chain having a top surface on
the
center link of the chain; and
Fig. 16 is a cross-sectional view through a cutter link having a top surface
formed
by deformation of a material segment of the main body of the cutter link.
Summary of The Invention
The cutter link of the present invention is characterized primarily in that
the support
surface and the top surface are surfaces that are separated from one another,
wherein the
support surface is formed by the end face of a support element of the cutter
link that is
disposed essentially parallel to the plane of the main body, wherein said top
surface comprises
a wider surface, approximately transverse to the direction of travel, of a
material segment of
a chain link, and wherein the top surface is lower than the support surface.
Embodying the support surface and the top surface separately enables their
simple and
different configuration, whereby to form the support surface different
structural measures can
be selected than for the formation of the top surface. For example, instead of
a bending away
a deformation of a material segment can also be advantageous for forming a
wider top surface
transverse to the direction of travel. In so doing, the otherwise necessary
magnitude required
for forming the support surface by bending away can be significantly reduced,
so that simple
structural means can be used to make a small support surface available that is
adequate for
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limiting the thickness of the chip that is to be cut and requires only a low
feed power. In
addition, the shape and position of the support surface can be selected
independently of the
shape and the position of the top surface, so that each support surface can be
individually
adapted to a particular application.
It should be emphasized that with the inventive configuration it is now also
possible to
easily limit the penetration depth of the support surface in a soft material
by the position,
configuration and size of the top surface without this having any effect upon
the size and
configuration of the support surface. In a simple manner the top surface is
disposed lower than
the support surface, so that with a designated use of the cutter link, i.e. a
saw chain provided
with the cutter link, merely the support surface rests against the material
that is to be cut, as
a result of which a high cutting efficiency is achieved with a low feed
pressure. If the feed
pressure of the cutter link into the material is improperly increased by the
user, the support
surface presses into the material, such as soft wood, whereby the top surface,
which is
disposed lower, effectively prevents a further penetration into the material
that is to be cut.
Due to the arrangement of support surface and top surface at different levels,
the user can,
within a permissible band width, increase the pressure of the cutter link upon
the material that
is to be cut without the top surface coming into engagement and the cutting
efficiency
dropping. The drop off in cutting efficiency occurs only if due to an
increased feed pressure
the top surface comes to rest against the material that is to be cut, as a
result of which the
necessary drive power for the cutter link significantly increases. In a
straightforward
manner, the support surface is formed by the end face of a support rib or
element on the main
body that is disposed essentially parallel to the plane of the main body, and
the top surface is
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formed from a tang of a material segment of the main body of the cutter link,
with the tang
being angled off approximately transverse to the direction of travel. It can
also be expedient
to provide the support surface on the cutter link itself, and to form the top
surface on a different
chain link, for example the center link.
Further specific features of the present invention will be described in detail
subsequently.
Description of Preferred Embodiments
Referring now to the drawings in detail, the cutter link 1 illustrated in
Figs. 1 and 2 is
intended as a side link in a chain saw for a power chain saw. Saw chains are,
of course,
known, with the construction of one such chain being described in the
aforementioned EP 0
712 700 A1.
The cutter link 1 comprises a main body 2, which has two rivet openings 3 for
the
connection of the cutter link 1 to further chain links. When the saw chain is
connected, the
cutter link 1 moves in the direction of travel 4, whereby a cutter tooth 6 is
formed on a rear
portion 5 of the cutter link 1 as viewed in the direction of travel 4. The
cutter tooth 6 has a
lateral cutting edge 7 that is disposed in the direction of travel 4, and also
has a top cutter 8
that is disposed transverse to the direction of travel 4. The approximately
vertical lateral
cutting edge 7 adjoins, without a transition, the horizontal top cutter 8 that
is disposed above
the main body 2 transverse to the direction of travel 4.
Leading or moving ahead of the cutter tooth 6 is a depth gauge or limiter 10
that in the
illustrated embodiment is formed on a front portion 9 of the main body 2 as
viewed in the
direction of travel 4. In this connection, the front portion 9 of the main
body 2 is divided into
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the support rib or element 11, which is disposed in the plane 13 of the main
body 2, as well as
a carrying rib or element 12 having a free end or material segment 14 which,
as can be seen
from Figs. 1 and 2, is bent away or to the side approximately perpendicular to
the plane of the
main body 2 relative to one longitudinal side 15 thereof. This longitudinal
side 15 of the main
body 2 faces the lateral cutting edge 7. The tang of the material segment 14
is bent away from
the longitudinal side 16 toward the longitudinal side 15, with the bent away
material segment
14 extending beyond the longitudinal side 15, as can be clearly seen in Fig.
2. The
longitudinal edge 17 of the bent-away tang extends parallel to the direction
of travel 4 and is
spaced slightly by the amount "u" from the plane 32 of the lateral cutting
edge 7 that is
disposed parallel to the main body 2.
The support element 11 is disposed on that side of the front portion 9 of the
main body
2 that faces the cutter tooth 6, and ends at a distance "v" below the top
cutter 8. The free end
face of the support element 11 forms a support surface 18, which preferably
extends
approximately parallel to a plane 20 of the cutter link 1 that extends through
the center axes
19 of the rivet openings 3. The plane 20 is disposed approximately parallel to
a guide surface
21 of a non-illustrated guide bar, upon which abutment surfaces 22 of the
cutter link 1, i.e. of
the main body 2 thereof, rest. With the saw chain connected, the cutter link 1
is moved along
the guide surface 21 of the guide bar in the direction of travel 4.
In the embodiment illustrated in Figs. 1 and 2, a top surface 23 leads or
moves ahead
of the support surface 18 of the depth limiter 10. The top surface 23 is
formed by the bent-
away tang of the free end of the material segment 14 of the carrying element
12. The top
surface 23, which preferably has a planar configuration, is expediently
disposed approximately
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parallel to the plane 20 defined by the center axes 19 of the rivet openings
3, whereby the top
surface 23 is disposed lower than the support surface 18 by the amount "t".
The support surface 18 and the top surface 23 are thus surfaces on the cutter
link 1 that
are separated from one another, so that the support surface 18, in conformity
with its
application, can be set for limiting the thickness of the chip that is to be
cut, whereas the top
surface 23 serves for limiting the penetration depth of the support surface 18
in soft material
at increased feed pressure or load and for this application can be configured
independently
of the configuration of the support surface 18. In so doing, the amount "t" is
designed such
that within the limit of a structurally prescribed band width, the user can
vary the feed pressure
utilized by him without the top surface 23 having to be used. Only if the user
applies an
inappropriately high feed pressure upon the cutter link 1 does the top surface
23 become
effective in order to limit a deep penetration of the support surface 18 in
the, for example, soft
material that is being cut.
The shape and position of the support surface 18 is expediently such that in
order to
move the cutter link 1 in the material being cut, such as wood, only a slight
feed pressure is
necessary, whereby an effective limiting of the thickness of the chip to be
cut is achieved.
Only if the cutter link is pressed too hard into the material being cut does
the top surface 23
become effective, whereby at the same time the drive power necessary for
moving the cutter
link through the material is increased. The cutting efficiency drops, since
the drive motor for
moving the saw chain has only a limited output. The user will therefore reduce
the feed
pressure applied by him upon the saw chain, as a result of which only the
support surface 18
becomes effective and a higher cutting efficiency results. The configuration
of the depth limiter
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thus holds the user to the proper guidance and handling of a power chain saw
while
providing a high cutting efficiency with a low tendency for kick back.
To achieve an appropriately large top surface 23, this top surface is wider
than the
support surface 18 in a direction transverse to the direction of travel 4. It
can be expedient to
make the top surface 23 longer than the support surface 18 in the direction of
travel 4.
In order to compensate for the difference in height between the top surface 23
and the
support surface 18, the width of which is determined by the thickness of the
main body 2, a
shoulder 28 is formed between the trailing edge 24 of the top surface 23 and
the leading edge
26 of the support surface 18; the shoulder 28 is preferably rounded. The top
surface 23
10 adjoins the leading edge 26 of the support surface 18, which leading edge
is disposed
transverse to the direction of travel 4, by means of the shoulder 28.
As shown in Fig. 1, the leading side 29 of the carrying element 12, together
with the
edge of the bent-away tang of the material segment 14, are beveled, resulting
in a leading
edge 30 on the side 20 below the tang 14.
The embodiment illustrated in Fig. 3 differs from that of Figs. 1 and 2 by the
tang 14,
which in this case is bent away in the direction toward the longitudinal side
16, with the free
longitudinal edge 17 of the tang being spaced by the slight amount "a" from a
plane 31 that
extends parallel to the plane 13 of the main body 2 and through which extends
the outermost
edge of the top cutter 8. In other respects, the construction corresponds to
that of the
embodiment illustrated in Figs. 1 and 2, for which reason the same components
are provided
with the same reference numerals.
In the embodiment illustrated in Fig. 4, in contrast to the embodiment of
Figs. 1 and 2
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the top surface is inclined in the direction of travel 4, whereby the leading
edge 25, which is
disposed transverse to the direction of travel 4, is disposed lower than the
trailing edge 24 of
the top surface 23. The leading edge 26 and the trailing edge 27 of the
support surface 18 are
disposed at the same level. With this configuration the top surface 23 has an
increased
utilization as a function of the feed pressure. In other words, the effective
surface 23 of the top
surface increases as the feed pressure increases. This can be advantageous in
an
appropriate application.
In the embodiment illustrated in Figs. 5 and 6, the depth limiter 10, which is
composed
of the support element 11 and the carrying element 12, is offset approximately
parallel out of
the plane 13 of the main body 2. In this way, the top surface 23 extends
approximately from
the plane 31, which contains the outer corner of the top cutter 8, to just
before the plane 32,
which is disposed on the other longitudinal side 15 of the main body 2,
extends parallel to the
plane 13 of the main body, and contains the outer edge of the lateral cutting
edge 7. Due to
the offset 33, the top surface 23 provides a support of the cutter tooth 6
that is effective over
the entire cutting width B. The support surface 18 for limiting the thickness
of the chip that is
to be cut is again formed exclusively by the free end face of the support
element 11 that is
offset out of the plane 13 of the main body 2. The trailing edge 27 of the
support surface 18,
in other words the edge that faces the top cutter 8, is in this connection
disposed at an angle
to the direction of travel 4; in the embodiment illustrated in Fig. 6, the
trailing edge 27 extends
approximately parallel to the top cutter 8.
In the embodiment illustrated in Figs. 7 and 8, the top surface 23 is disposed
between
the cutter tooth 6 and the support surface 18. This configuration allows for a
greater spacing
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of the support surface 18 from the cutter tooth 6, which can be advantageous
in conjunction
with the size of the cutter tooth and the intended application.
As shown in Fig. 7, a rounded portion 34 adjoins the leading edge 26 and
merges with
the leading side 35 of the support element 11. The trailing edge 27, as can be
seen in the top
view of Fig. 8, is approximately aligned with the leading edge 25 of the top
surface 23. In this
connection, the top surface 23 drops in the direction of travel 4, so that its
leading edge 25 is
lower than the trailing edge 24.
It can be expedient for the top surface 23 to rise in the direction of travel
4, as illustrated
in Fig. 9. In such an embodiment, the trailing edge 24 of the top surface 23
that faces the
cutter tooth 6 is disposed lower than the leading edge 25 which, in a manner
similar to that
shown in the top view of Fig. 8, is aligned approximately with the trailing
edge 27 of the support
surface 18. In other respects, the embodiment of Fig. 9 corresponds to that of
Figs. 7 and 8,
so that the same reference numerals are used to indicate the same components.
In the embodiment illustrated in Fig. 10, the top surface 23 is disposed
between the
support surface 18 and the cutter tooth 6 such that the leading edge 25 of the
top surface 23
is disposed on the same level as the trailing edge 27 of the support surface
18. As soon as
the support surface penetrates soft material that is being cut, the top
surface 23 immediately
becomes effective, whereby due to the rise in the direction of travel, as the
feed pressure
increases a greater portion of the top surface 23 becomes effective. Such an
embodiment can
be expedient where extremely soft material is being cut.
In the embodiment illustrated in Fig. 12, in contrast to the embodiment of
Figs. 10 and
11 the trailing edge 24 of the surface 23 is provided at the level of the
plane of the support
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surface 18. The trailing edge 24 is thus disposed at the same level as the
leading edge 26 and
trailing edge 27 of the support surface 18. In other respects the construction
of the cutter link
of Fig. 12 corresponds to that of Figs. 10 and 11, for which reason the same
parts are
designated by the same reference numerals.
It can also be expedient to associate with the support surface 18 both a
leading top
surface 36 as well as a trailing top surface 38, as shown in Figs. 13 and 14.
The two top
surfaces 36 and 38 are preferably provided with the same width transverse to
the direction of
travel 4, whereby the length of the leading top surface 36 as measured in the
direction of travel
is expediently slightly greater than the length of the trailing top surface
38. As can be seen in
Fig. 13, the trailing edge 40 of the leading top surface 36 is disposed by the
distance "t" from
the plane of the support surface 18, whereby, as shown in Fig. 14, the leading
edge 26 of the
support surface 18, when viewed in plan, is approximately aligned with the
trailing edge 40 of
the leading top surface 36. In this connection, the top surface 36 drops in
the direction of
travel 4, whereby its leading edge 41 is disposed lower than the plane of the
trailing top
surface 38. This top surface 38 is disposed approximately parallel to the
plane 20 defined by
the center axes 19 of the rivet opening 3, and is lower than the support
surface 18 by the
amount T. The amount T is greater than the amount "t"; in the illustrated
embodiment, the
amount T is approximately twice as great as the amount "t".
The leading edge 37 of the trailing top surface 38 is, as can be seen in the
plan view
of Fig. 14, approximately aligned with the trailing edge 27 of the support
surface 18, with the
trailing edge 39 of the trailing top surface 38 facing the cutter tooth 6.
Whereas in the embodiments of Figs. 1 to 14 the depth limiter 10 is provided
with the
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support surface 18 and top surface 23 or top surfaces 36 and 38 on the main
body 2 of the
cutter link 1, Fig. 15 shows an embodiment where the main body 2 is provided
with the cutter
tooth 6 and the support surface 18, while the top surface 23 is provided on
another chain link
that is adjacent to the cutter link 1. In Fig. 15, the top surface 23 is
provided on the center link
45 of the connected saw chain. For this purpose, the center link 45 has an
upright carrying
element 12 that is disposed in the plane of the center link 45 and the free
end of which forms
the material segment 14 on which the top surface 23 is formed. In the
embodiment of Fig. 15,
the top surface 23 is achieved by deformation in the direction of the arrow
44, resulting in the
top surface 23 which is wider transverse to the direction of travel of the saw
chain. As shown
in Fig. 15, the deformation is preferably effected symmetrically relative to
the plane of the
center link 45.
The cutter link 1, which is connected by a rivet 43 with the center link 45
and a side link
46, is provided merely with the support surface 18, which is disposed higher
by the amount "t"
and which, as in the previous embodiments, is formed by the end face of the
free end of a
support element 11. The support element 11 is offset outwardly parallel to the
plane 13 of the
cutter link 1 and is disposed close to the lateral cutting edge 7, while the
top surface 23 is
spaced slightly to the side of the support surface 18. In this connection, the
top surface 23
extends beyond the inner side 42 toward the side link 46. As viewed in plan,
the top surface
23 is disposed next to the support surface 18 transverse to the direction of
travel.
The embodiment illustrated in Fig. 16 corresponds fundamentally to the
structure of Fig.
1, for which purpose the same components have the same reference numerals.
However, in
contrast to the embodiment of Fig. 1 in this embodiment the top surface 23,
similar to the
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illustration in Fig. 15, is formed by a deformed material segment 14 that is
formed on the end
of the carrying element 12 of a front portion 9 of the main body 2 of the
cutter link 1. The top
surface 23 is thus possible not only by bending away the free, tang-like end
of the material
segment 14, but also by a deformation thereof, preferably in the direction of
the arrow 44 as
shown in Fig. 15.
The specification incorporates by reference the disclosure of German priority
documents
199 38 223.9 of 12 August 1999 and 199 40 496.6 of 26 August 1999.
The present invention is, of course, in no way restricted to the specific
disclosure of the
specification and drawings, but also encompasses any modifications within the
scope of the
appended claims.
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